Human hair is treated nowadays with cosmetic hair preparations in many ways. These include, for example, cleaning the hair with shampoos, care and regeneration using rinses and therapies, and bleaching, coloring, and reshaping the hair using coloring agents, toning agents, waving agents, and styling preparations. Agents for modifying or tinting the color of head hair play a predominant role in this context.
For temporary coloring, it is usual to use coloring or toning agents that contain so-called substantive dyes as a coloring component. These are dye molecules that absorb directly onto the hair and do not require an oxidizing process in order to form the color. Included among these dyes are, for example, henna, which has been known since antiquity for coloring the body and hair. These colors are, as a result, much more sensitive to shampooing than are the oxidation-based colors, so that a (very often undesirable) shift in tint, or even a visible loss of color, then occurs much more quickly.
So-called oxidizing coloring agents are used for permanent, intense coloring results with corresponding fastness properties. Such coloring agents usually contain oxidation dye precursors, so-called developer components and coupler components. The developer components, under the influence of oxidizing agents or atmospheric oxygen, form among one another, or by coupling with one or more coupler components, the actual dyes. The oxidizing coloring agents are notable for outstanding, long-lasting color results. For natural-looking coloring results, it is usually necessary to use a mixture of a larger number of oxidation dye precursors; in many cases, substantive dyes are also used for toning.
These coloring agents, in particular oxidizing coloring agents or hair-bleaching powders, are as a rule manufactured by manually mixing prefabricated active-substance compositions, for example two oxidizing coloring agents or two bleaching agents. Manual intermixing is, however, time- and labor-intensive; for example, the constituents need to be weighed out before mixing. In addition, homogenization of the mixture by manual mixing of the active substances is time-intensive. The user is furthermore exposed to dust that may occur when processing solid active-substance compositions.
In light of this, US patent application 2005/0169871 A1 (L'Oreal) describes a method for manufacturing active-substance mixtures for hair treatment in which method a liquid is directed, at elevated temperature and at a pressure above 3 bar, through a polymer-containing preparation. Although this method is suitable for manufacturing a mixture of the active substances being used, the mixture obtained nevertheless, because of its inhomogeneity and insufficient viscosity, leaves room for improvement especially for utilization in hair coloring.